Which structure is an insertion of the brachialis?

Which structure is an insertion of the brachialis?

• A. Olecranon of ulna
• B. Coronoid process of ulna
• C. Coronoid process of ulna and ulna tuberosity
• D. Radial tuberosity

Answer: (B)

The brachialis attaches to the ulna, with its distal attachments anchoring on the front of the ulna near the elbow. Its primary insertion is the coronoid process of the ulna, and it also has attachment onto the nearby ulna tuberosity. This makes it a strong elbow flexor regardless of forearm position, since its line of pull acts on the ulna to bring the forearm toward the humerus. In contrast, the olecranon is the insertion site for the triceps, and the radial tuberosity is where the biceps brachii inserts, so those structures are not for the brachialis. Therefore, the coronoid process of the ulna is a key insertion point for the brachialis. (Note: some descriptions also mention the ulna tuberosity as part of its distal attachment.)

The brachialis attaches to the ulna, with its distal attachments anchoring on the front of the ulna near the elbow. Its primary insertion is the coronoid process of the ulna, and it also has attachment onto the nearby ulna tuberosity. This makes it a strong elbow flexor regardless of forearm position, since its line of pull acts on the ulna to bring the forearm toward the humerus. In contrast, the olecranon is the insertion site for the triceps, and the radial tuberosity is where the biceps brachii inserts, so those structures are not for the brachialis. Therefore, the coronoid process of the ulna is a key insertion point for the brachialis. (Note: some descriptions also mention the ulna tuberosity as part of its distal attachment.)